Battery packs are used in various stationary and mobile systems to power one or more electric machines and electronic devices. Electric motor generator units are one type of electric machine that is commonly used to provide or store electrical energy in a system. For instance, an electric motor/generator unit may draw electrical energy from the battery pack in order to deliver torque to one or more gear sets or other rotating members of a power transmission. Such motor/generator units may also be used to generate rather than consume electricity, and thereby recharge the battery pack or power the electronic devices.
Because voltage levels suitable for use in certain applications can be relatively high, voltage isolation is required in any electrical circuit used to connect the battery pack to the remainder of the system. Typically, a battery disconnect unit is used that includes high-power fuses and high-voltage mechanical contactors to isolate the DC voltage bus from the battery pack and provide galvanic isolation when the system is turned off or during an electrical fault. However, the size, weight, and cost of high-voltage contactors and fuses may be less than optimal.